Double-walled metallic vacuum container

ABSTRACT

A metallic double-walled vacuum container is provided which improves heat insulating property and resistance to vibration. It has a metallic inner shell and an outer shell. The end face of the inner shell is constricted so as to rise inwardly. The inner end of a mouth pipe is inserted into and joined to the constricted portion to form a mouth portion of the inner shell and the outer end of the mouth pipe is joined to the outer shell.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a metallic double-walled vacuum container.

[0002] As shown in FIG. 13A, a conventional metallic vacuum container is of a double-walled structure having an inner shell 1 and an outer shell 2 and made of a metal such as stainless steel. The inner shell 1 has a mouth portion 5 protruding outwardly (downwardly in the figure) from an end face 4 thereof. The outer peripheral surface of the mouth portion 5 at its tip is joined to a mouth portion 10 of the outer shell 2. The hollow space between the inner and outer shells 1 and 2 is evacuated through an evacuating tip 6. As an example of use, an arrangement is shown in which a plug 7 is inserted in the inner shell mouth portion 5, a liquid inlet 8 and a liquid outlet 9 are provided in the plug 7, and an overflow pipe 11 is connected to the inner end of the liquid outlet 9 (JP utility model publication 7-27430).

[0003] Further, 12 designates a heat-insulating metallic foil, 13 a getter for drawing residual gas, and 14 a bracket. The overflow pipe 11 is connected to the plug 7 through a holder 11′. The bracket 14 is welded to the end face 3 of the outer shell 2 and a presser plate 23 for the plug 7 is fixed to the bracket 14.

[0004] The vacuum container is used e.g. as a heat accumulator, and with the trunk portion of the outer shell 2 fixed to the container body, liquid heated to a predetermined temperature is supplied through the liquid inlet 8. The liquid is kept hot inside, and by supplying additional liquid through the liquid inlet 8 as necessary, the liquid kept hot is discharged to outside through the liquid outlet 9 via the overflow pipe 11.

[0005] In such a vacuum double-walled container, as a means for increasing heat insulating property, it is preferable to prolong the inner shell mouth portion 5 because the heat insulating distance is increased. But provided the trunk diameter and the container height are the same, the volume decreases by an amount corresponding to the increase in the length of the inner shell mouth portion 5 (see chain line in FIG. 13A). Also, in use, if a vibrating load acts on the container body, crack may develop in the welded portion of the bracket 14. This is because vibration of the inner shell 1, which resonates with the vibration of the device body, is transmitted to the end face 3 of the outer shell 2 through the mouth portion 5 of the inner shell 1.

[0006] On the other hand, in order to increase heat insulating property, it is conceivable to reduce the diameter of the mouth portion 5 of the inner shell 1. But drawing is time-consuming and increases the cost.

[0007] In order to avoid drawing, as shown in FIG. 13B, a combined structure is feasible in which the mouth portion 5 is formed by a mouth pipe 16, which is a separate member from the inner shell 1 and is welded to the end face 4 of the inner shell 1.

[0008] But if such a double-walled vacuum container as in FIG. 13B is used in the manner as described above, one problem is that when a vibrating load is produced, crack may develop at the welded portion between the mouth pipe 16 and the end face 4 of the inner shell 1.

[0009] An object of this invention is to provide a metallic double-walled vacuum container which does not cause a reduction in volume even if the mouth portion of the inner shell is lengthened, and which has an increased strength against vibrating loads.

SUMMARY OF THE INVENTION

[0010] According to this invention, there is provided a metallic double-walled vacuum container comprising a metallic inner shell, a metallic outer shell having a mouth portion and an end face at an open side, a space formed between the inner and outer shells being evacuated, the inner shell having an end face at an open side constricted to form a constricted portion rising inwardly, a mouth pipe having an inner end thereof inserted into and joined to the constricted portion, the mouth pipe having an outer end thereof joined to the mouth portion of the outer shell.

[0011] With this arrangement, it is possible to lengthen the mouth portion by an amount equal to the rising amount of the constricted portion formed on the inner shell. The heat insulating property is increased correspondingly. Also, the joint portion of the mouth pipe to the inner shell is supported by the constricted portion provided on the inner shell. Since the constricted portion allows deformation, vibrating loads transferred to the mouth pipe is absorbed by the constricted portion. This prevents cracking of the joint portion of the mouth pipe.

[0012] Also, by providing the end face of the inner shell close to the end face of the outer shell, an annular hollow space may be provided around the constricted portion. With this arrangement, the mouth portion of the inner shell lengthens, so that the heat insulating property improves. Also the volume of the entire container can be increased by an amount equal to the volume of the annular hollow space.

[0013] A heat insulating member for preventing direct contact of the inner shell with the outer shell may be provided on the outer periphery of the top and/or bottom end of the trunk of the inner shell. With this arrangement, it is possible to shut off heat transfer due to direct contact and to prevent generation of metal-to-metal contact sound.

[0014] As another means for achieving the object of increasing strength against vibrating loads, according to this invention, there is also provided a metallic double-walled vacuum container comprising a metallic inner shell having a mouth portion, a metallic outer shell having a mouth portion, the mouth portion of the inner shell being joined to the mouth portion of the outer shell, a space formed between the inner and outer shells being evacuated, a plug member fitted in the mouth portion of the inner shell, a presser plate in abutment with the plug member, and a bracket fixed to the outer periphery of the outer shell, the presser plate being coupled to the bracket.

[0015] With this arrangement, since the bracket is fixed to the outer peripheral surface of the outer shell, which is at a position remote from the end face of the outer shell, which tends to be subjected to vibration, cracking at the welded portion due to vibration is prevented.

[0016] Further, as another means for achieving the object of increasing strength against vibrating loads, there is also provided a metallic double-walled vacuum container comprising a metallic inner shell having a mouth portion, a metallic outer shell having a mouth portion, the mouth portion of the inner shell being joined to the mouth portion of the outer shell, a space formed between the inner and outer shells being evacuated, the outer shell having a cylindrical portion at lower end of its mouth portion, the cylindrical portion being disposed around the mouth portion of the inner shell and having its lower end joined to the mouth portion of the inner shell, a plug member fitted in the mouth portion of the inner shell, a presser plate in abutment with the plug member, and a bracket fixed to the outer periphery of the outer shell, the presser plate being coupled to the bracket.

[0017] With this arrangement, vibration acting on the welded portion of the bracket is absorbed at the cylindrical portion of the outer shell. Thus cracking is prevented.

[0018] Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a sectional view of a first embodiment;

[0020]FIG. 2 is a sectional view of a second embodiment;

[0021]FIG. 3 is a sectional view of a third embodiment;

[0022]FIG. 4 is a sectional view of a fourth embodiment;

[0023]FIG. 5 is a perspective view of a presser plate of the same;

[0024]FIG. 6 is a sectional view of a fifth embodiment;

[0025]FIG. 7 is a perspective view of a presser plate of the same;

[0026]FIG. 8 is a sectional view of a sixth embodiment;

[0027]FIG. 9A is a perspective view of semi-annular brackets of the same;

[0028]FIG. 9B is a perspective view of a presser plate of the same;

[0029]FIG. 10 is a sectional view of a seventh embodiment;

[0030]FIG. 11 is a perspective view of a presser plate of the same;

[0031]FIG. 12 is a sectional view of an eighth embodiment; and

[0032]FIGS. 13A and 13B are sectional views of a conventional container.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinbelow, the embodiments of this invention will be described with reference to the attached drawings.

[0034] The first embodiment shown in FIG. 1 comprises, as with the above-described conventional one, an inner shell 1 and an outer shell 2, both made of a metal such as stainless steel. The inner shell 1 has a mouth portion 5 formed by providing a constricted portion 15 rising inwardly in a tapered manner by a height H at the central portion of an end face 4 of the inner shell 1 and around an opening, inserting the inner end of a metallic mouth pipe 16 into a top opening 21 of the constricted portion 15 and joining it by welding, and joining by welding the outer end of the mouth pipe 16 to a mouth portion 10 of the outer shell 2 as with the conventional container.

[0035] Otherwise, this embodiment is the same as the conventional container in that air between the inner and outer shells is evacuated through the evacuating tip 6, that a metal foil 12 for heat insulation covers the inner shell 1, that the getter 13 is mounted, that the bracket 14 is fixed to the end face 3 of the outer shell 2 by welding, and that the presser plate 23 for the plug 7 is coupled to the bracket 14.

[0036] In the structure of the first embodiment, compared with the conventional one, since the mouth portion 5 of the inner shell 1 is lengthened by an amount equal to the height H of the constricted portion 15, the heat insulating effect increases correspondingly. Also, the joint portion at the top end of the mouth pipe 16 is supported by the tapered constricted portion 15 provided at the end face 4 of the inner shell 1. Since the constricted portion 15 allows deformation, vibration transmitted from the inner shell 1 to the mouth pipe 16 is absorbed at the constricted portion 15. As a result, formation of cracks in the joint portion between the mouth pipe 16 and the top end 21 of the constricted portion 15 is prevented.

[0037] In the second embodiment shown in FIG. 2, the end face 4 of the inner shell 1 is formed deeper by a distance H′ downwardly than in the conventional one (shown by chain line) so as to be closer to the end face 3 of the outer shell 2. The second embodiment is the same as the first embodiment in that at the end face 4, a tapered constricted portion 15 is provided to rise inwardly, that the inner end of the mouth pipe 16 is inserted into and joined to the top end 21, and that the bottom end of the mouth pipe 16 is joined to the mouth portion 10 of the end face 3 of the outer shell 2 to form the mouth portion 5 of the inner shell 1, and in other structures.

[0038] With this arrangement, as with the first embodiment, since the mouth portion 5 is prolonged by the amount equal to the height H of the constricted portion 15, the heat insulating property improves. Also, the constricted portion 15 improves the vibration absorbing property at the joint portion between the mouth pipe 16 and the top end 21 of the constricted portion 15. Also, the volume of the entire container increases by the amount equal to the annular space 17 having a height H′.

[0039] Further, as shown in FIG. 2, by sticking heat insulating members 19 to the top and bottom ends of a trunk portion 18 of the inner shell 1 over the entire circumference thereof, it is possible to prevent direct contact between the outer shell 2 and the inner shell 1, insulate heat and prevent sounding. The inner shell 1 and the outer shell 2 may be in close contact with each other through the heat insulating members 19. The heat insulating members may be provided not over the entire circumference but only at several points spaced in the circumferential direction.

[0040] In the third embodiment shown in FIG. 3, by providing the mouth pipe 16 with a corrugated portion 20, heat insulating effect is increased without increasing the entire length of the mouth pipe 16.

[0041] Next, the vacuum container of the fourth embodiment shown in FIGS. 4 and 5 differs from the prior art shown in FIG. 13A in that the evacuating tip 6 is provided on top of the outer shell 2, and that a cover cap 22 is fixed by welding to the outer shell 2 to cover it. But it is essentially the same in other structures. Thus, the same numerals are attached to identical parts and their description is omitted.

[0042] In this embodiment, a plurality of radial leg pieces 24 (FIG. 5) are provided on a circular presser plate 23 which is pressed against the bottom end of the plug 7. The presser plate 23 is formed with two holes 8′ and 9′ so as to align with the liquid inlet 8 and liquid outlet 9, respectively. In the tip of each leg piece 24, a hole 25 for coupling is formed.

[0043] Four L-shaped brackets 26 corresponding to the leg pieces 24 are arranged on the trunk portion of the outer shell 2 at equal angular intervals and have their upper ends joined to the trunk portion. The bottom ends of the respective brackets 26 protrude beyond the end face 3, superposed on the tip portions of the respective leg pieces 24, and fixed together by screws 27. While the brackets 26 are described as four separate members, they may be a single annular member having an L-shaped section.

[0044] With this arrangement, since the brackets 26 are welded to the outer peripheral surface of the outer shell 2, at a position remote from the mouth portion of the container, which tends to be influenced by vibration of the inner shell 1, cracking at the welding portion is prevented.

[0045] The fifth embodiment shown in FIG. 6 differs from the fourth embodiment in the shape of the presser plate 23 and the manner of coupling. As shown in FIG. 7, the presser plate 23 in this embodiment is provided with protrusions 28 at quadrisected positions on its peripheral edge and a rope hole 29 is formed in each protrusion 28. Also, L-shaped brackets 30 are welded to the outer peripheral surface of the outer shell 2. By passing ropes 31 between the brackets 30 and the protrusions 28 through the rope holes 29 and tightening the ropes, the brackets 30 and the presser plate 23 are fixed together. With this arrangement, as in the fourth embodiment, cracking at the welded portions of the brackets 30 is prevented.

[0046] In the sixth embodiment shown in FIGS. 8, 9A and 9B, instead of the brackets 30, a pair of semi-annular brackets 32 have one end thereof coupled by a hinge 34′, fitted in an annular groove 33 formed in the outer peripheral surface of the outer shell 2, and coupled together by a bolt 34 with a nut (FIG. 9A). Ropes 37 are passed between rope holes 36 formed in protrusions 35 provided on the the semi-annular brackets 32 and rope holes 29 formed in the presser plate 23 (FIG. 9B) and are tightened to couple them together. In this embodiment, there is no need to weld the brackets 32 to the outer shell 2, so that cracking will not occur.

[0047] In the seventh embodiment shown in FIGS. 10 and 11, belt holes 39 are formed in protrusions 38 provided on the presser plate 23, and a belt 41 is passed over the outer shell 2 and the cover cap 22 between two opposed belt holes 39 to tighten them together. In this embodiment, too, since there is no welded portion, cracking will not occur.

[0048] In the eighth embodiment shown in FIG. 12, the inner portion of the end face 3 of the outer shell 2 is constricted to provide a cylindrical portion 42, which is fitted around the inner shell mouth portion 5 with a predetermined gap and joined directly to the mouth portion 5. But it may be indirectly joined through an interposed member.

[0049] The bracket 14 in this embodiment is, as with the first embodiment (FIG. 1), joined to the end face 3 of the outer shell 2 around the cylindrical portion 42 by welding. In this embodiment, since vibration is absorbed and relaxed by the cylindrical portion 42, cracking at the welded portion of the bracket 14 is prevented.

[0050] As described above, according to this invention, since the length of the mouth portion is increased by an amount equal to the height of the inwardly directed constricted portion provided on the inner shell, the heat insulating property improves and the durability against vibrating loads on the inner shell end face increases. Also, by forming the end face of the inner shell so as to be deeper toward the outer shell, it is possible to increase the container volume by an amount equal to the annular hollow space formed around the constricted portion.

[0051] Further, by providing the brackets coupled to the plug presser plate at a position where they are less liable to be affected by vibration, employing means for fixing the plug presser plate without such brackets, or providing the cylindrical portion at the lower portion of the outer shell, it is possible to improve durability against vibrating loads. 

What is claimed is:
 1. A metallic double-walled vacuum container comprising a metallic inner shell, a metallic outer shell having a mouth portion and an end face at an open side, a space formed between said inner and outer shells being evacuated, said inner shell having an end face at an open side constricted to form a constricted portion rising inwardly, a mouth pipe having an inner end thereof inserted into and joined to said constricted portion, said mouth pipe having an outer end thereof joined to the mouth portion of said outer shell.
 2. The metallic double-walled vacuum container as claimed in claim 1 wherein an annular hollow space is provided around said constricted portion by providing the end face of said inner shell close to the end face of said outer shell.
 3. The metallic double-walled vacuum container as claimed in claim 1 or 2 wherein a heat insulating member for preventing direct contact of said inner shell with said outer shell is provided on the outer periphery of at least one of the top and bottom ends of the trunk of said inner shell.
 4. A metallic double-walled vacuum container comprising a metallic inner shell having a mouth portion, a metallic outer shell having a mouth portion, the mouth portion of said inner shell being joined to the mouth portion of said outer shell, a space formed between said inner and outer shells being evacuated, a plug member fitted in the mouth portion of said inner shell, a presser plate in abutment with said plug member, and a bracket fixed to the outer periphery of said outer shell, said presser plate being coupled to said bracket.
 5. A metallic double-walled vacuum container comprising a metallic inner shell having a mouth portion, a metallic outer shell having a mouth portion, the mouth portion of said inner shell being joined to the mouth portion of said outer shell, a space formed between said inner and outer shells being evacuated, said outer shell having a cylindrical portion at lower end of its mouth portion, said cylindrical portion being disposed around the mouth portion of said inner shell and having its lower end joined to the mouth portion of said inner shell, a plug member fitted in the mouth portion of said inner shell, a presser plate in abutment with said plug member, and a bracket fixed to the outer periphery of said outer shell, said presser plate being coupled to said bracket. 